CF1409D Decrease the Sum of Digits

You are given a positive integer $ n $ . In one move, you can increase $ n $ by one (i.e. make $ n := n + 1 $ ). Your task is to find the minimum number of moves you need to perform in order to make the sum of digits of $ n $ be less than or equal to $ s $ . You have to answer $ t $ independent test cases.

The first line of the input contains one integer $ t $ ( $ 1 \le t \le 2 \cdot 10^4 $ ) — the number of test cases. Then $ t $ test cases follow. The only line of the test case contains two integers $ n $ and $ s $ ( $ 1 \le n \le 10^{18} $ ; $ 1 \le s \le 162 $ ).

For each test case, print the answer: the minimum number of moves you need to perform in order to make the sum of digits of $ n $ be less than or equal to $ s $ .